Code P0300, multiple random misfire

Tiny
IKE H
  • MEMBER
  • 1997 MITSUBISHI MONTERO
  • 3.5L
  • V6
  • 4WD
  • AUTOMATIC
  • 185,000 MILES
Dtc P0300 changed plugs and wires swapped ICM with known good, one swapped coils with known good ones, and still have the same problem. No change in engine performance. Problem getting worse affecting drivability.
Friday, July 1st, 2022 AT 4:07 AM

3 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,323 POSTS
This can be because you have a weak fuel pump, clogged fuel filter or a bad MAF/MAP sensor. Neither the MAF nor MAP sensor will show up in a code you just need to try them. Here is a guide to help you check the fuel pump pressure and the location of the fuel filter, MAP and MAF sensors. Check out the diagrams (below). Let us know what happens and please upload pictures or videos of the problem.
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Friday, July 1st, 2022 AT 6:37 PM
Tiny
IKE H
  • MEMBER
  • 3 POSTS
I changed the fuel filter it has been about 7 years. Then I went to check the map sensor I figured if I had it running and unplugged it I would notice a difference in engine performance. There was no difference in performance when I unplugged it. Is that a good sign that it's bad?
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Saturday, July 2nd, 2022 AT 2:34 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,323 POSTS
Yep, if no change it doesn't sound like it is providing any feed back data to the computer.
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Sunday, July 3rd, 2022 AT 10:36 AM

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